Air conditioning system utilizing refrigeration



May 25, 1943. 71'. PALMER I "AIR CONDITIONING SYSTEM UTILIZING REFRIGERATION Filed Sept. 8, 1939 3 )3. b win I flnufl B mung s a P// k kl- INVENTOR I WW: 1%

Patented May 25, 1943 AIR CONDITIONING SYSTEM UTILIZING REFRIGERATION Robert T. Palmer, Sharon, Mass, 'assignor to B. F. Sturtevant Company, Boston, Mass.

Application September 8, 1939, Serial No. 233,939

1 Claim.

This invention relates to air conditioning systems utilizing refrigeration and relates more particularly to air conditioning systems utilizing refrigerant compressors, for railway passenger cars.

In the past,. it has been the practice in air conditioned railway passenger cars, to supply 75% recirculated air and 25% outdoor air. Utiliningsuch large proportions of recirculated air reduces the refrigerating load but the conditioned air does not have the desired freshness and the odors are objectionable.

This invention provides for utilizing all outdoor air except at such times that the refrigeration plant will be overloaded or the expense of conditioning all outdoor air is out of proportion to the benefits.

An object of the invention is to increase the a proportion of outdoor air supplied in air conditioning systems.

Another object of the invention is to control the supply of outdoor air in an air conditioning system by a thermostat which indicates the load upon the refrigerant compressor used.

Other objects of the invention will be apparent from the following description taken with the drawing.

The invention will now be described with reference to the drawing which illustrates diagrammatically one embodiment of the invention in a railway passenger car.

The blower draws in outdoor air through the inlet 6, and recirculated air through the inlet 1,

and forces the air through the air cooler 8 and then through the duct 9 into the passenger space. The electric motor Ill drives the refrigerant 4 compressor H which supplies refrigerant to the condenser i2 and then through the pipe l3 and expansion valve it through the direct expansion tubes d in the air cooler 8. the evaporated refrigerant returning through the pipe is to the suction side of the compressor,

The iresh air inlet 8 contains the dampers l6 and the recirculated air inlet I contains the dampers it which are adjusted by the electric motor i8 under the control of the duct thermostat it.

The thermostat in the passenger space controls the operation or the compressor It. When the temperature in the passenger space rises above the control temperature, which may be 75 F., the contacts of the thermostat 20 close and complete the electric circuit including the wire 25, the electric source 23, the wire 24, the motor it and the wire 25.

This energizes the compressor H, causing it to supply refrigerant to the air cooler 8 for chilling the air moved through the cooler and supplied into the passenger space.

The duct thermostat I 9 is connected in the electric circuit including the wire 26, the electric source 23, the wire 2?, the damper motor is and the wire 28.

The contacts of the duct thermostat is are adjusted to close for temperatures below say F. When the air from the cooler is below 65 F., the contacts of the relay I Q close the last described circuit including the damper motor l8 causing it to adjust the dampers ii to closed position and the dampers It to full open position. The cooler 8 then chills all outdoor air and n0 recirculated air is supplied into the passenger space.

If the condition of the outdoor air becomes such that the refrigeration equipment becomes overloaded or the load upon it becomes such that conditioning all outdoor air would not be practical, the evaporator tubes d will not be able to chill the air below the desired control temperature of 65 F., and the duct thermostat is will open its contacts to open the above described electric circuit including the damper motor i8, causing the motor is to adjust the dampers i6 and H to partial recirculation.

During the 011 cycles of-the compressor, there will be no chilled air from the cooler 23 to actuate the thermostat ls and the dampers will be adjusted for partial recirculation.

The temperature and pressure of the refrigerant vapor in the suction pipe 15 also reflect the condition of the evaporator tubes 6, that is.

whether they are overloaded or not. The thermostat 29 may be connected to the suction pipe iii to respond to the temperature or pressure therein or to both and may be connected as shown by the dotted lines on the drawing or as an alternate control in substitution for the duct thermostat l9.

What is claimed is:

An air cooling system comprising refrigerant evaporator tubes arranged as air cooling tubes, means for supplying outdoor air and air recirculaited from the space served, to said tubes for cooling, refrigerating means including a compressor for supplying refrigerant to said tubes, means including a thermostat in the space served for controlling said compressor, means forming an outlet for the air from said tubes, into said space, and means including a second thermostat exposed to the air from said tubes and located between said tubes and said outlet, for adjusting said first mentioned means to portion of outdoor air when the temperature of the air from said tubes is below a predetermined point and for increasing the proportion of recirculated air when the temperature of the air leaving said tubes is above said point.

ROBERT T. PALMER.

increase the pro- 

